Convective Outlook: Thu 17 Nov 2016
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Thu 17 Nov 2016 - 05:59 UTC Fri 18 Nov 2016

ISSUED 21:15 UTC Wed 16 Nov 2016

ISSUED BY: Dan

A sharpening upper trough will slide SE-wards on Thursday, introducing notably steep lapse rates as a result of cold mid-levels atop seasonably warm SSTs. On the forward side of this upper trough, a squally cold front/instant occlusion will move eastwards across the southern half of the British Isles. Despite convective depth being largely too shallow for lightning (at least marginally so, hence isolated sferics cannot be ruled out), some 50-70kts DLS with a notable wind veer along the front may allow segments of line convection to develop capable of squally gusts of wind and perhaps a tornado. Brief episodes of heavy rain, small hail and a rapid temperature drop are typically produced with such features.


In the post-frontal environment, numerous showers are expected, heaviest and most frequent in western areas where some sporadic lightning will be likely. Overall instability is too marginal to warrant any SLGT areas for now, but the risk is generally greatest near western coasts and over open seas. Again, gusty winds and small hail will be possible with the most intense showers, with snow at increasingly lower elevations in northern and western Britain as the day progresses.